The primary purpose of this proposed research program is to develop a general strategy for the synthesis of alkaloid natural products by a novel approach which features the intramolecular (4 plus 2) cycloaddition reactions of nitrogen substituted dienophiles and dienes. Although this methodology should in principle be applicable to the syntheses of an enormously wide range of alkaloids possessing hydroindole, hydroquinoline or related ring systems, particular attention is being directed toward the syntheses of biologically-active alkaloids of the Erythrina, Amaryllidaceae, Aspidosperma, Iboga, and Lycopodium families.